New insights into switchable MOF structures at the MX beamlines

Metal-organic framework compounds (MOFs) are widely used in gas storage, material separation, sensor technology or catalysis. A team led by Prof. Dr. Stefan Kaskel, TU Dresden, has now investigated a special class of these MOFs at the MX beamlines of BESSY II. These are “switchable” MOFs that can react to external stimuli. Their analysis shows how the behaviour of the material is related to transitions between ordered and disordered phases. The results have now been published in Nature Chemistry.

Metal-organic framework compounds (MOFs) consist of inorganic and organic groups and are characterised by a large number of pores into which other molecules can be incorporated. MOFs are therefore interesting for many applications, for example for the storage of gases, but also for substance separation, sensor technology or catalysis. Some of these MOF structures react to different guest molecules by changing their structures. They are thus considered switchable.

Read more on the HZB website

Image: View into a MOF crystal exemplified by DUT-8. The massive pores are clearly discernible.

Credit: © TU Dresden

Gene encapsulation with MOFs for new delivery vectors in gene therapy

A research team from RMIT University, CSIRO Manufacturing, University of New South Wales, Graz University of Technology and the University of Adelaide, in Australia, have demonstrated an easy and efficient method to use nano MOFs for carrying large-size intact gene sets to be applied in gene therapy. Their study reports encapsulation of a complete gene-set in zeolitic imidazolate framework-8 (ZIF-8) MOFs and cellular expression of the gene delivered by the nano MOF composites, with data obtained at the MISTRAL beamline at the ALBA Synchrotron showing intracellular presence of the biocomposite particles.

MOFs (metal-organic frameworks) are porous materials with well-defined geometry and high loading capacity. For biological applications, their high porosity makes these composites an effective strategy for loading and protection of proteins; however, their use for other biomacromolecules such as nucleic acids is still in their infancy. Now, a research team lead by RMIT University from Melbourne has been studying the use of ZIF-8 MOFs as possible gene delivery vectors. The results show encapsulation of a gene-set in ZIF-8 MOFs and its cellular expression, proving that MOFs do not damage the structural and functional activity of the cargo nucleic acid, essential for possible applications in gene therapy as disease treatments.

>Read more on the ALBA website

Image: Left: Confocal laser scanning microscope images of plGFP@ZIF-8 transfected into human prostate cancer epithelial cells. See the entire image here.

Probing the complex dielectric properties of MOFs

Gaining fundamental insights into the full dielectric behaviour of MOFs across the infrared and THz.

An international team of researchers from Oxford, Diamond, and Turin, has demonstrated the novel use of synchrotron radiation infrared (SRIR) reflectivity experiments, to measure the complex and broadband dielectric properties of metal-organic framework (MOFs) materials. Open framework compounds like MOFs have the potential to revolutionise the field of low-k dielectrics, because of their tuneable porosity coupled with an enormous combination of physicochemical properties not found in conventional systems. Furthermore, next generation IR optical sensors and high-speed terahertz (THz) communication technologies will stand to benefit from an improved understanding of the fundamental structure-property relations underpinning novel THz dielectric materials.

>Read more on the Diamond Light Source website

Image: (extract) The high-resolution reflectivity data obtained were subsequently used to determine the real and imaginary components of the complex dielectric function by adopting the Kramers−Kronig Transformation theory.
Credit: ACS

The power of Metal-Organic Frameworks

Trapping nuclear waste at the molecular level

Nuclear power currently supplies just over 10% of the world’s electricity. However one factor hindering its wider implementation is the confinement of dangerous substances produced during the nuclear waste disposal process. One such bi-product of the disposal process is airborne radioactive iodine that, if ingested, poses a significant health risk to humans.  The need for a high capacity, stable iodine store that has a minimised system volume is apparent – and this collaborative research project may have found a solution.

Researchers have successfully used ultra-stable MOFs to confine large amounts of iodine to an exceptionally dense area. A number of complementary experimental techniques, including measurements taken at Diamond Light Source and ISIS Neutron and Muon Source, were coupled with theoretical modelling to understand the interaction of iodine within the MOF pores at the molecular level.

High resolution x-ray powder diffraction (PXRD) data were collected at Diamond’s I11 beamline. The stability and evolution of the MOF pore was monitored as the iodine was loaded into the structure. Comparison of the loaded and empty samples revealed the framework not only adsorbed but retained the iodine within its structure.

>Read more on the Diamond Light Source website

Illustration: Airborne radioactive iodine is one of the bi-products of the nuclear waste disposal process. A recent study involving Diamond Light Source and ISIS Neutron and Muon Source showed how MOFs can capture and store iodine which may have implications for the future confinement of these hazardous substances.